1 /*
2 * Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
3 *
4 * Use of this source code is governed by a BSD-style license
5 * that can be found in the LICENSE file in the root of the source
6 * tree. An additional intellectual property rights grant can be found
7 * in the file PATENTS. All contributing project authors may
8 * be found in the AUTHORS file in the root of the source tree.
9 */
10
11 #include "rtc_base/numerics/mod_ops.h"
12
13 #include <stdint.h>
14
15 #include "test/gtest.h"
16
17 namespace webrtc {
18 class TestModOps : public ::testing::Test {
19 protected:
20 // Can't use std::numeric_limits<unsigned long>::max() since
21 // MSVC doesn't support constexpr.
22 static const unsigned long ulmax = ~0ul; // NOLINT
23 };
24
TEST_F(TestModOps,Add)25 TEST_F(TestModOps, Add) {
26 const int D = 100;
27 ASSERT_EQ(1u, Add<D>(0, 1));
28 ASSERT_EQ(0u, Add<D>(0, D));
29 for (int i = 0; i < D; ++i)
30 ASSERT_EQ(0u, Add<D>(i, D - i));
31
32 int t = 37;
33 uint8_t a = t;
34 for (int i = 0; i < 256; ++i) {
35 ASSERT_EQ(a, static_cast<uint8_t>(t));
36 t = Add<256>(t, 1);
37 ++a;
38 }
39 }
40
TEST_F(TestModOps,AddLarge)41 TEST_F(TestModOps, AddLarge) {
42 const unsigned long D = ulmax - 10ul; // NOLINT
43 unsigned long l = D - 1ul; // NOLINT
44 ASSERT_EQ(D - 2ul, Add<D>(l, l));
45 ASSERT_EQ(9ul, Add<D>(l, ulmax));
46 ASSERT_EQ(10ul, Add<D>(0ul, ulmax));
47 }
48
TEST_F(TestModOps,Subtract)49 TEST_F(TestModOps, Subtract) {
50 const int D = 100;
51 ASSERT_EQ(99u, Subtract<D>(0, 1));
52 ASSERT_EQ(0u, Subtract<D>(0, D));
53 for (int i = 0; i < D; ++i)
54 ASSERT_EQ(0u, Subtract<D>(i, D + i));
55
56 int t = 37;
57 uint8_t a = t;
58 for (int i = 0; i < 256; ++i) {
59 ASSERT_EQ(a, static_cast<uint8_t>(t));
60 t = Subtract<256>(t, 1);
61 --a;
62 }
63 }
64
TEST_F(TestModOps,SubtractLarge)65 TEST_F(TestModOps, SubtractLarge) {
66 // NOLINTNEXTLINE
67 const unsigned long D = ulmax - 10ul; // NOLINT
68 unsigned long l = D - 1ul; // NOLINT
69 ASSERT_EQ(0ul, Subtract<D>(l, l));
70 ASSERT_EQ(D - 11ul, Subtract<D>(l, ulmax));
71 ASSERT_EQ(D - 10ul, Subtract<D>(0ul, ulmax));
72 }
73
TEST_F(TestModOps,ForwardDiff)74 TEST_F(TestModOps, ForwardDiff) {
75 ASSERT_EQ(0u, ForwardDiff(4711u, 4711u));
76
77 uint8_t x = 0;
78 uint8_t y = 255;
79 for (int i = 0; i < 256; ++i) {
80 ASSERT_EQ(255u, ForwardDiff(x, y));
81 ++x;
82 ++y;
83 }
84
85 int yi = 255;
86 for (int i = 0; i < 256; ++i) {
87 ASSERT_EQ(255u, ForwardDiff<uint8_t>(x, yi));
88 ++x;
89 ++yi;
90 }
91 }
92
TEST_F(TestModOps,ForwardDiffWithDivisor)93 TEST_F(TestModOps, ForwardDiffWithDivisor) {
94 ASSERT_EQ(122, (ForwardDiff<uint8_t, 123>(0, 122)));
95 ASSERT_EQ(0, (ForwardDiff<uint8_t, 123>(122, 122)));
96 ASSERT_EQ(122, (ForwardDiff<uint8_t, 123>(1, 0)));
97 ASSERT_EQ(0, (ForwardDiff<uint8_t, 123>(0, 0)));
98 ASSERT_EQ(1, (ForwardDiff<uint8_t, 123>(122, 0)));
99 }
100
TEST_F(TestModOps,ReverseDiff)101 TEST_F(TestModOps, ReverseDiff) {
102 ASSERT_EQ(0u, ReverseDiff(4711u, 4711u));
103
104 uint8_t x = 0;
105 uint8_t y = 255;
106 for (int i = 0; i < 256; ++i) {
107 ASSERT_EQ(1u, ReverseDiff(x, y));
108 ++x;
109 ++y;
110 }
111
112 int yi = 255;
113 for (int i = 0; i < 256; ++i) {
114 ASSERT_EQ(1u, ReverseDiff<uint8_t>(x, yi));
115 ++x;
116 ++yi;
117 }
118 }
119
TEST_F(TestModOps,ReverseDiffWithDivisor)120 TEST_F(TestModOps, ReverseDiffWithDivisor) {
121 ASSERT_EQ(1, (ReverseDiff<uint8_t, 123>(0, 122)));
122 ASSERT_EQ(0, (ReverseDiff<uint8_t, 123>(122, 122)));
123 ASSERT_EQ(1, (ReverseDiff<uint8_t, 123>(1, 0)));
124 ASSERT_EQ(0, (ReverseDiff<uint8_t, 123>(0, 0)));
125 ASSERT_EQ(122, (ReverseDiff<uint8_t, 123>(122, 0)));
126 }
127
TEST_F(TestModOps,MinDiff)128 TEST_F(TestModOps, MinDiff) {
129 for (uint16_t i = 0; i < 256; ++i) {
130 ASSERT_EQ(0, MinDiff<uint8_t>(i, i));
131 ASSERT_EQ(1, MinDiff<uint8_t>(i - 1, i));
132 ASSERT_EQ(1, MinDiff<uint8_t>(i + 1, i));
133 }
134
135 for (uint8_t i = 0; i < 128; ++i)
136 ASSERT_EQ(i, MinDiff<uint8_t>(0, i));
137
138 for (uint8_t i = 0; i < 128; ++i)
139 ASSERT_EQ(128 - i, MinDiff<uint8_t>(0, 128 + i));
140 }
141
TEST_F(TestModOps,MinDiffWitDivisor)142 TEST_F(TestModOps, MinDiffWitDivisor) {
143 ASSERT_EQ(5u, (MinDiff<uint8_t, 11>(0, 5)));
144 ASSERT_EQ(5u, (MinDiff<uint8_t, 11>(0, 6)));
145 ASSERT_EQ(5u, (MinDiff<uint8_t, 11>(5, 0)));
146 ASSERT_EQ(5u, (MinDiff<uint8_t, 11>(6, 0)));
147
148 const uint16_t D = 4711;
149
150 for (uint16_t i = 0; i < D / 2; ++i)
151 ASSERT_EQ(i, (MinDiff<uint16_t, D>(0, i)));
152
153 ASSERT_EQ(D / 2, (MinDiff<uint16_t, D>(0, D / 2)));
154
155 for (uint16_t i = 0; i < D / 2; ++i)
156 ASSERT_EQ(D / 2 - i, (MinDiff<uint16_t, D>(0, D / 2 - i)));
157 }
158
159 } // namespace webrtc
160